I just typed this in response to a different thread like 10 minutes ago, so I'll just copy and past it here for your convenience:
There are lots of threads that discuss this topic, but basically outpatient hours are relatively easily obtained by simply calling clinics and asking to be an observer. If any PTs who treated you in the past would remember you (or even if they wouldn't) that would be a good place to start (assuming you are still in the area). Try to split those outpatient hours up among more than one place (eg. do 30 or 40 at a peds clinic and/or another 30 or 40 at a standard outpatient ortho clinic and/or another 30 or 40 at a hand therapy clinic that has a PT (not an OT!), rather than like 100 hours in one clinic). Inpatient hours are much more difficult to setup in general. Inpatient hours in SNF's and some rehab facilities can be a bit easier to get into, in some cases, but can still take several weeks to successfully get started. Acute care hospital hours are the most involved to get into and generally allow the smallest number of hours, but having acute care hours is a huge boon to your application as PT adcoms really like to see them. Start working on getting inpatient hours early (like 6 months or more before you plan to apply). I waited til a couple of months before application submission time to start trying to set up acute care hours, and while it ended up working out, it was very stressful waiting for people who never reply to emails and jumping through hoops for two months before I could even start. Ultimately, if you could do something like 30 or 40 hours in a rehab facility or SNF and 20 hours in the acute care hospital setting that would be ideal. Having hundreds of hours can be good, but is only worth doing if you are working as a PT tech anyway and getting paid for it. Maximizing the variety of your observation experiences is much more important than increasing your total number of hours. Breadth is valued much, much, much more than depth in the admissions process. And GPA and GRE scores will always be the two biggest criteria, so remember not to let your grades slip in the name of doing lots of observation hours. How many hours you do a week or how you get the hours done chronologically is irrelevant, the number of hours you ultimately have when you apply and the number of different settings you have seen is what matters, not your weekly time commitment.